Flight controls mixing lever



Jan. 7, 1958 J. M. llART FLIGHT CONTROLS MIiXING LEVER Filed Aug, 12,1955 FLIGHT CONTROLS MIXING LEVER Jack M. Hart, Lockport, N. Y.,assignor, by mesne assignments, to the United States of America asrepresented by the Secretary of the Navy The present invention relatesto a multi-rotor helicopter control system, and more particularly to ameans for combining a plurality of input signals in order to obtain adesired plurality of output control signals to actuate the variousmovable airfoil surfaces of the helicopter.

The usual flight control system of a multi-rotor helicopter is apositive mechanical type with control tubes, bell cranks, idlers andmixing levers operated by conventional helicopter controls. The pilotflies the helicopter by actuating the usual foot pedals, sticks, andother movable control inputs. According to the instant invention, theseinputs are transmitted through control tubes and bell cranks to a mixinglever system which mixes or combines various control inputs and in turntransmits output signals through control tubes and bell cranks to thelinks that incline the swash plates, raise and lower the collectivepitch sleeves and perform other functions to control the cyclic pitchand collective pitch'of the helicopter rotors.

Accordingly, it is an object of this invention to provide an improvedmixing lever system to mix the controls on a multi-rotor so that thesame set of controls can serve several functions independently of eachother.

A particular object of this invention is to provide a mixing leverassembly wherein the collective pitch of the fore and aft rotor may beadjusted equally and simultaneously.

Another object is to provide a mixing lever assembly wherein the trimactuator will simultaneously move the collective pitch outputs to thefore and aft rotors in opposite directions.

Another object is to provide a mixing lever assembly wherein actuationof the fore and aft cyclic pitch input will cause the collective pitchoutputs to the fore and aft rotors to move in opposite directions.

Another object is to provide a mechanical movement having a plurality ofinputs and a plurality of outputs wherein two of said outputs can becaused to move simultaneously in one direction or simultaneously inopposite directions.

The specific nature of this invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

Figure 1 is a perspective view of the mixing lever means of the instantinvention; and

Figure 2 is a view of the upper portion of the mixing lever means takenon the plane indicated by line 2--2 of Figure 1.

Referring to Figures 1 and 2, the mixing lever assembly comprises amixing lever support arm or link 1, pivoted by pivot pin 2 to supportbracket 3. Bracket 3 is preferably fixed to the port frame structure ofthe helicopter. The other end of mixing levers support arm 1 isbifurcated to provide extensions 4 and 5 for receiving cross link 6.Cross link 6 is furcated to provide extensions 7, 8 and 9.

As viewed in Figure 2, a single pivot pin pivots one end of mixing leversupport arm 1 to cross link 6 and to end portion 11 of forward and aftcyclic pitch mixing triangular bell crank 21. Extensions 7 and 8 arereceived by extensions 4 and 5, and extensions 8 and 9 receive extension5 and end portion 11 of triangular bell crank 21. Cyclic pitch inputpush pull tube 19, which is preferably actuated by a pilots cycliccontrol stick through a bell crank lever, is pivoted on pivot pin 10adjacent to extension 7 between extensions 7 and 8. Fore and aft cyclicpitch output push pull tube 28 is preferably pivoted on pivot pin 10adjacent to extension 8 between extensions 7 and 8.

The other end of cross link 6 is bifurcated to provide extensions 12 and13 for pivoting push pull tube 17 on pivot pin 14. Collective pitchinput push pull tube 17 may be actuated by levers which are preferablymounted at the left side of the pilots and co-pilots seats. Extension 13of cross link 6 is preferably provided with a transverse extension 15for pivoting the center of one of the side portions of collective pitchmixing triangular bell crank 18 on pivot pin 14.

One end portion of collective pitch mixing lever bell crank 18 isprovided with extensions 29 and 31) for pivoting the collective pitchoutput forward rotor push-pull tube 31 on pivot pin 32. A second endportion of collective pitch bell crank 28 is provided with pivot pin 33mounted between extensions 34 and 35 for pivoting collective pitch aftrotor push pull tube 36 to bell crank 18.

A cross link 43 arranged parallel to cross link 6 is vided withextensions 40 and 41 for pivoting therebetween trim input link 42.

Operation -In operation, the collective pitch control system is ac-vtuated by the pilots levers. The levers move push pull tube 17 up ordown. This rotates link 6 about pivot 10 thereby moving collective pitchoutputs 31 and 36 in the same direction. Since cross link 6 and 43 plusthe vertical legs of hell cranks 18 and 21 form a parallelogram,collective pitch output tubes 31 and 36 move equally and parallel.Therefore the pitch of the rotor blades of each rotor is increased ordecreased simultaneously and equally.

Actuation of corrective trim input link 42 rotates bell crank 21 aboutpivot 10 thereby moving link 43 and rotating bell crank 18 about pivot14 to move the collective pitch outputs 31 and 36 in oppositedirections. Hence, the trim of the aircraft is controlled.

When cyclic pitch input push pull tube 19 is actuated by the pilotscyclic control stick, mixing levers support arm 1 is rotated about pivot2 thereby displacing bell crank 21, moving cross link 43, rotating bellcrank 18 about pivot 14, and moving collective pitch output pushpulltubes 31 and 36 in opposite directions. This also causes a movement ofcorrective trim link 42.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. A flight controls mixing means for a two rotor helicopter comprisinga first triangular bell crank, a first link pivoted at one of its endsto a first end portion of said first triangular bell crank, a secondtriangular bell crank pivoted at the center of one of its side portionsto the other end of said first link, a second link parallel to the firstlink pivoted at one of its ends to a second end portion of said firsttriangular bell crank and at its other end to a first end portion ofsaid second triangular bell Patented Jan. 7, 1958 crank,.athird linkpivoted: at one of its ends to theframe of the helicopter and. at itsotheraend .to therfirsttendlportion of said first triangular bell crank,output linkage to control the collective pitch of the fore helicopterrotor pivoted1to a second end portioncof: said secondatriangular bellcrank, output linkage to control 3 the collective; pitch ofthe'afthelicopter rotor;.pivoted to .a third endportion of said :secondtriangularibell crank, ioutput linkagezto control the fore and afthelicopterrotors .cyclic pitch pivoted to the first end iportionsof saidfirst triangular bell crank, collective "pitchtinputtlinkage pivotedtothe center of the side portion of5the-second' triangularbell crank formoving the fore and aft collective pitch-output linkages equally and:parallel, corrective trim input 2 linkage pivotedto the :third:endaportion of said: first triangular bell crank for rotatingsaidi'fi'rstibell crank, moving said second link and-rotating saidsecond! bell crank toithereby move the'fore and aft .colleetivepitchoutputrlinkages in opposite directions, and fore and aft cyclic pitchinput linkage pivoted-to the first 'end'portioniof said first triangularbell .crank for displaeingsaid first Ebellzerank, moving said secondlink, and rotating said second bell crankttorthereby move the fore andaft collective' output linkages in opposite directions.

2. z t-mechanical movementcornprising a firstltriangular bellacrank, afirst link pivoted at one of itsends to alfirst end portion ofsaid-first-triangular bell crank, a secondtriangular'bell crank-pivotedat the center of one of its side portions to the other end-of said firstlink, a secondlink parallel to'the first linkpivoted at one of itsendsto a -second end portion-of said-first triangular bellcrank and at itsother e'nd toafirst end portion of said second triangular bell crank, aithird link pivoted atone of its-ends'to a fixed mounting means and atits other 'end to the first end portion'of said first triangular-bellcrank, a first-outputpivoted-to a second end portion of said secondtriangular bell crank, asecond output pivoted to a thirdtendiportion ofsaid second triangular bell crank, a third output pivoted to the firstend portion of said first triangular'bell'crank, a first'input pivoted'to the center ofthe side portion of the second triangular bell crankfor'movirigthe first'and second outputs equally and'parallel, a secondinputpivoted tothe third end portion "of said firsttrianguiar bell crankforrotating said'first bell 'crank'movin g said second link and rotatingsaid second bellcran'kito thereby move 'the first and second outputs inopposite directions, and a third input pivoted 'to'the first end portionof said first triangular bell crank for actuating said third output anddisplacing said' first'bell 'crankym'ovingsaidsecond link,and

end to a first end'portion of said second 'tr'ianguiarbell crank, output'l'inkage'to .controrthe collectivepitch 'of the fore helicopter rotorpivoted to a, second end portion of said secondnia'ngular' bell crank,outputliiikage to control the c llective pitch of thea'fth'elicQptenrotc-r pivoted 'to a third end portion of "saidtsecondtriangular bell crank, and collective pitch input linkage ,pivote'dtothe center of the side "portion of the second triangular bell crank formoving the fore and aft collective pitch output linkages equally andparallel.

4. A'mechanieal'movernentcomprising' a first triangular bei'l .crank, afirst link'pivoted'iat one' ofits ends'to a first end portion of said"first triangular 'bell "crank, 21 second triangular he'llcranlqpivoted"attlre':center'of one of its side portions toth'e"otl'ieffill'd 'of said first link,

a second link parallel to the first link pivoted at one of its tends .to.a second end ,portion wof said first triangular bell crank and at itsother end to a firstend portion or" said second triangular bell crank, afirst output pivoted to a second end portion of said second triangularbell crank, a second output pivoted to a third end portion of saidsecond triangular bellcrank, and an input pivoted to the center of theside portion of the second triangular bell crank'ffor moving the first.and secondoutputscqually and parallel.

5. 'Afiight controls mixing'means :for a two rotor helicopter comprisinga first triangular belllcrank, .a firstrlink pivoted at one of its endsto a first end portion of said first triangularbell: crank, -'asecondtriangular-bell crank pivoted at the center of one of its sideportions to the other end of said'first link, a second link parallel tothe first link pivoted at one of its ends to a second end portion ofsaid first triangular bell crank and at its other end to aifirstrend.portionrof said second triangular bell'crank, a thirdlink pivoted lat:one ofiits'zends .toatheframe of the helicopter and :atits *other end'to the first end "portion of said first tiiangulanbell crank,LQutputlIinkage .to control the collective pitch "of the fore-helicopterrotor-pivoted: to a se'conden'd portion-of said second triangular bellcrank, outputllin kage to controlithe collectivepitchiof the afthelicopter rotor. pivoteda'tou'a third end portion i of said secondtriangular bell L'cran k,- and collective pitch input linkage pivoted tothe center ofthe side 'portion of the second triangular hell i crank formoving the. fore and aft collective pitch output linkages equally andparallel.

6. A mechanical movement compr-isinga first triangular bellcrank, afirst link pivoted at oneof its en'ds-to-a first end portion of I saidfirst triangular bell "crank, a second triangular bell crank pivoted atthe center of one of its side p'ort ions to'the other=end iof said firstlink, a secondlinlcparallel to the first linkpivoted atonecf its ends toa sec'on'd end portion 'of'said first triangular bell crank and at'itsotherendto a firstend portion of said second triangular bell-crankpathird link pivoted-at one of its ends to th'e 'frame=o'f the helicopterandat its other end-to'thd'first end-portion of said first triangularbell crank, a first output L pivoted to a second: end portion of saidsecond triangular-bell crank, a-second output pivoted to athird endportion of said second triangular bell crank, and an input pivoted tothe-'center of the side portion ofthe second triangular bell crank formoving the first and second outputs equally and parallel.

7. A flight controls mixing means'for a'two rotor helic'optercomprisinga' first'tiiangular'bell crank, a first'link pivoted at oneend of its en'ds toafirstend portion-of said first triangular bellcrank, 21 second triangular bell crank pivoted at'thecenter o'fone ofitsside portions to the other end of said first link, a second linkparallel to the first linkpiv'oted at one of its ends to-a second endportion of said'first triangularbell crankand atits other end to a firstend portion of said second triangular he'll crank, a third link-pivotedatone of its ends to the frameof the'helicopter and at its otherend to"th'e 'first end portion of said first triangular bell crank, outputlinkage to control the-collective pitch of the fore helicopter rotorpivoted to' a second end portion -'of said second triangular bell crank,'output linkage to con'trol the collective pitch or the aft "helicopterrotor 'pivoted to a third end portion of said second triangular bellcrank, output linkage to control the fore and aftdre'licopter rotorscyclic'piteh pivoted to the first end portion of said first triangular'bell crank, and -'collective' pitch input linkage pivoted -to-the"center of the side portion ofthe second triangulafbell' crank formoving thefore' and aft collective pitch; output linkages equally andparallel. '8. A mechanical movement comprising a first triangularbellcrank, a first link pivoted at one 'of'its ends to a first end portionof said first triangular -bell crank, a second triangular bell' crankpivoted at the center of one or its'side portions tothe other'end ofsaid first link,

a second link parallel to the first link pivoted at one of its ends to asecond end portion of said first triangular bell crank and at its otherend to a first end portion of said second triangular bell crank, a thirdlink pivoted at one of its ends to the frame of the helicopter and atits other end to the first end portion of said first triangular bellcrank, a first output pivoted to a second end portion of said secondtriangular bell crank, a second output pivoted to a third end portion ofsaid second triangular bell crank, a third output pivoted to the firstend portion of said first triangular bell crank, and an input pivoted tothe first end portion of said first triangular bell crank for actuatingsaid third output and displacing said first bell crank, moving saidsecond link, and rotating said second bell crank to thereby move thefirst and second outputs in opposite directions.

9. A flight controls mixing means for a two rotor helicopter comprisinga first triangular bell crank, a first link pivoted at one of its endsto a first end portion of said first triangular bell crank, a secondtriangular bell crank pivoted at the center of one of its side portionsto the other end of said first link, a second link parallel to the firstlink pivoted at one of its ends to a second end portion of said firsttriangular bell crank and at its other end to a first end portion ofsaid second triangular bell crank, output linkage to control thecollective pitch of the fore helicopter rotor pivoted to a second endportion of said second triangular bell crank, output linkage to controlthe collective pitch of the aft helicopter rotor pivoted to a third endportion of said second triangular bell crank, and corrective trim inputlinkage pivoted to the third end portion of said first triangular bellcrank for rotating said first bell crank, moving said second link androtating said second bell crank to thereby move the fore and aftcollective pitch output linkages in opposite directions.

10. A flight controls mixing means for a two rotor helicopter comprisinga first triangular bell crank, a first link pivoted at one of its endsto a first end portion of said first triangular bell crank, a secondtriangular bell crank pivoted at the center of one of its side portionsto the other end of said first link, a second link parallel to the firstlink pivoted at one of its ends to a second end portion of said firsttriangular bell crank and at its other end to a first end portion ofsaid second triangular bell crank, a third link pivoted at one of itsends to the frame of the helicopter and at its other end to the firstend portion of said first triangular bell crank, output linkage tocontrol the collective pitch of the fore helicopter rotor pivoted to asecond end portion of said second triangular bell crank, output linkageto control the collective pitch of the aft helicopter rotor pivoted to athird end portion of said second triangular bell crank, and correctivetrim input linkage pivoted to the third end portion of said firsttriangular bell crank for rotating said first bell crank, moving saidsecond link and rotating said second bell crank to thereby move the foreand aft collective pitch output linkages in opposite directions.

11. A mechanical movement comprising a first triangular bell crank, afirst link pivoted at one of its ends to a first end portion of saidfirst triangular bell crank, a second triangular bell crank pivoted atthe center of one of its side portions to the other end of said firstlink, a second link parallel to the first link pivoted at one of itsends to a second end portion of said first triangular bell crank and atits other end to a first end portion of said second triangular bellcrank, a first output pivoted to a second end portion of said secondtriangular bell crank, a second output pivoted to a third end portion ofsaid second triangular bell crank, and input linkage provided to thethird end portion of said first triangular bell crank for rotating saidfirst bell crank moving said second link and rotating said second bellcrank to thereby move the first and second outputs in oppositedirections.

12. A mechanical movement comprising a first triangular bell crank, afirst link pivoted at one of its ends to a first end portion of saidfirst triangular bell crank, a second triangular bell crank pivoted atthe center of one of its side portions to the other end of said firstlink, a second link parallel to the first link pivoted at one of itsends to a second end portion of said first triangular bell crank and atits other end to a first end portion of said second triangular bellcrank, a third link pivoted at one of its ends to the frame of thehelicopter and at its other end to the first end portion of said firsttriangular bell crank, a first output pivoted to a second end portion ofsaid second triangular bell crank, a second output pivoted to a thirdend portion of said second triangular bell crank, and input linkagepivoted to the third end portion of said first triangular bell crank forrotating said first bell crank moving said second link and rotating saidsecond bell crank to thereby move the first and second out puts inopposite directions.

References Cited in the file of this patent UNITED STATES PATENTS2,454,981 Vint Nov. 30, 1948 2,549,969 Heseman Apr. 24, 1951 2,603,033Sharp July 15, 1952 FOREIGN PATENTS 28,612. Great Britain Dec. 24, 1903of 1902

